How to toggle attribute in jQuery

Question

I'm trying to use images as checkboxes. The following would work fine if it were radios instead of checkboxes that I was targeting but with checkboxes the problem is I can't select an element by clicking on it again after selecting it.

// image checkbox
$('#imageCheckBoxes img').click(function() {
    $(this).parent('span').find('input:checkbox').attr('checked', 'checked');
});

<div id="imageCheckBoxes">
    <ul>
        <li><a href="">Africa</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
        <li><a href="">Asia/Pacific Islands</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
        <li><a href="">Australia</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
        <li><a href="">Central/South America</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
        <li><a href="">Europe/Russia</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
        <li><a href="">North America</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
        <li><a href="">United Kingdom</a>  <span><img src="images/checkbox-inactive.png" /><input type="checkbox" name="" value="" /></span>
        </li>
    </ul>
</div>

I need to basically toggle the check attr() part.

How to do that?

Answer 1

I'd do this by passing a function to prop (since jQuery 1.6, attr before). The return value of this is set as the new property value.

$(this)
    .closest('li')
        .find('input:checkbox').prop('checked', function(idx, oldProp) {
            return !oldProp;
        });

The key fact here is that you can pass true or false to prop to set the checked property. oldProp is the existing value of the property (which will be either true or false), so !oldProp is the inversion: checked elements are unchecked and vice versa.

Note that I have also changed your code to look for the closest ancestor li element with closest, which should be more reliable and effective.

Answer 2

You could add a rather basic jQuery extension, that works in the same way as "toggle()" and "toggle(showOrHide)" but for attributes - "toggleAttr(attribute)" and "toggleAttr(attribute, addOrRemove)"

$.fn.toggleAttr = function(a, b) {
    var c = (b === undefined);
    return this.each(function() {
        if((c && !$(this).is("["+a+"]")) || (!c && b)) $(this).attr(a,a);
        else $(this).removeAttr(a);
    });
};

Note, this is xhtml compatible, and is designed for attributes such as "disabled", "enabled", "checked", "selected" and so on.

Example of use (for your scenario):

$('#imageCheckBoxes img').click(function() {
    $(this).parent('span').find('input:checkbox').toggleAttr('checked');
}

EDIT - though as pointed out by artlung - a label is probably best for your scenario